Missions

A particularly intriguing feature of Quaternary climate change (from 2.58 Myr onwards), is that there was a shift in the cyclicity in Earth's climate response to orbital forcing during the Mid-Pleistocene Transition (MPT) at around 1 Myr ago. Before the MPT cold glacial and warm interglacial periods alternated with a cyclicity of 40 kyr but after the MPT this cyclicity shifts to 100 kyr. Reasons for this shift remain unclear.

Among all the different palaeo records, only ice cores allow for a direct measurement of greenhouse gas concentration, thus providing a direct and quantitative information about past climate forcing and its atmospheric response. However, the longest record available to date, the EPICA Dome C (EDC) in Antarctica, only covers the last 800 kyr. This is why there is an active field of research within the ice core community to be able to extract and analyse ice that predates the MPT.

Within this framework, this postdoc position will be dedicated to numerical simulations of the Antarctic ice sheet on the million year timescale. The general objective is to quantify the possible impact of past changes in ice sheet geometry on ice core analysis. Notably, can oceanic and/or atmospheric changes alter ice dynamics to ultimately affect dome positions and age-depth relationship?

Here we will use the GRISLI thermo-mechanically coupled ice sheet model which includes a passive tracer transport model to simulate the ice sheet stratigraphy. We will use an ensemble of ice sheet simulations spanning a range of ice sheet parameters values and a variety of past climatic evolutions, to fully explore the different sources of uncertainties. This ensemble will be used to assess the occurrence of dome migrations in the past and their impact on ice sheet flow lines, in particular at the location of deep ice core locations.

Activities

- Run an ensemble of ice sheet model simulations;
- Confront model outputs to palaeo data to score the different members;
- Implement various climate forcing scenarios for the ice sheet model;
- Draft a paper on model results.

Skills

- Phd in Climate Science or Glaciology;
- Programming skills (Fortran) and experience of working in a Linux environment (shell scripts,...);
- Experience with climate data manipulation (e.g. netcdf format, nco, cdo, …);
- Written and oral communication skills in English. Knowledge of the French language would be convenient but not mandatory.
- Capacités de communication en Anglais, écrites et orales. La connaissance du Français n'est pas obligatoire.

Work Context

The French ANR ToBE (Towards Beyond EPICA) is strongly connected to the European H2020 project Beyond EPICA (2019-2026) that aims at recovering a 1.5 Myr ice core in the vicinity of Dome C in Antarctica (https://www.beyondepica.eu/en/). The ToBE project develops new analytical and numerical methods to help the interpretation of the European H2020 Beyond EPICA drilling project.

The position will be based at Orme des Merisiers (Gif-sur-Yvette) within the Laboratoire des Sciences du Climat et de l'Environnement (LSCE), a research institute supported by the CEA, the CNRS and the University of Versailles Saint-Quentin en Yvelines (UVSQ). LSCE is part of the Institut Pierre Simon Laplace (IPSL) that gathers nine research institutes of the Greater Paris region working on climate and environment. The LSCE employs 320 researchers, ingineers and administrative staffs, 150 permanent chercheurs, ingénieurs et agents administratifs, including 150 permanent staffs and about 50 phd students. The person recruited will join the climate modelling team (CLIM) and will work closely with the main developers of the GRISLI ice sheet model. Interactions and collaborations are also expected with the French ice core community, at LSCE and at the Institut des Géosciences de l'Environnement (IGE, UMR5001).

The position is located in a sector under the protection of scientific and technical potential (PPST), and therefore requires, in accordance with the regulations, that your arrival is authorized by the competent authority of the MESR.